Coupling for conduits



Sept; 17, 1963 J. w. MYERS 3,104,120

COUPLING FOR CONDUiTS Original Filed June 28, 1954 IN VEN TOR.

United States Patent 3,104,120 COUPLING FOR CONDUITS John W. Myers,Balboa Island, Calif assignor of onetenth to Brodie Ahlport, LosAngeles, Calif., and June L. Myers, administratrix of said John W.Myers, deceased, assignor of nine-tenths to June L. Myers, Corona delMar, Calif.

Continuation of application Ser. No. 439,533, June 28,

1954. This application Dec. 1, 1958, Ser. No. 777,321

2 filaims. (Cl. 285-461) This invention relates generally to pipejoints, and more particularly to means for joining pipes or conduits tosheet metal walls. lllustratively, and in its present primaryapplication, :the invention deals specifically with a coupling means forjoining an electrical conduit pipe to the wall of a switch box or thelike. This application is a continuation of my copending application,entitled, Coupling for Conduits, filed June 28, 1954, Serial No.439,533.

In the trade, a coupling for joining an electrical conduit to a sheetmetal wall of a switch box or the like is known as a hub. Various formsof hubs have been provided in the past, but none, insofar as I am aware,has met in a simple, inexpensive and satisfactory manner all of thethree principal requirements for such hubas are specified in existingelectrical codes. These are: (1) low electrical resistance through thecoupling, i.e., from the conduit to the electrically grounded switchbox, the measurement usually being made from the conduit to ground; (2)that the hub, when installed, be capable of withstanding a specifiedtorque, e. g., 1000' inch pounds for a 1-l /2 inch conduit; (3) that thehub be completely weatherproof.

It is accordingly a primary object of the invention to satisfy thesethree basic requirements in an improved manner, i.e., to provide a hubaffording a very low resistance connect-ion to the sheet metal wall towhich it is joined, one which tightens readily and easily to a highvalue of torque, and one which is absolutely fluid-tight when installed.

A further object is to satisfy the above primary purposes in a novel hubwhich is simple, inexpensive, and capable of being quickly, easily andinexpensively installed.

The invention can most easily be understood by referring now to thefollowing detailed description of certain present illustrativeembodiments, reference being had to the accompanying drawings, in which:

FIG. 1 shows in perspective a sheet metal switch box with a pair ofconduits joined thereto by hubs in accordance with the invention;

FIG. 2 shows the hub of the invention in vertical longitudinal section,joined to the wall of a switch box;

FIG. 3 is an exploded view of the hub;

FIG. 4 is the face view of a nut member forming one part of the hub; and

FIG. 5 shows a modfication.

In the drawings, numeral designates generally a conventional switch box,:such as may be installed in a position exposed to the weather, and at11 are designated usual electrical conduit pipes joined by hubs 12 tothe rear sheet metal wall 13 of box '10.

Wall 13 has a circular aperture 14, formed in the usual way, and anexternal hub part 15 on conduit 11 is in the form of a collar or annulushaving a somewhat reduced rearward tubular part 15a, having internalthreads 16 for engagement with the threaded end of conduit 11, thecollar having a further reduced tubular externally screw threaded part15b projecting therefrom and entering aperture 14, as shown. Collar 15has an annular front face 17 confronting and engaging the exterior face3,1911% Patented Sept. 17, 1963 of wall 13. A nut member 18 is screwedonto the tubular member 1511 of collar 15 that protrudes throughaperture 14 into the interior of the switch box when the face 17 ofcollar 15 is in engagement with wall 13. The nut 18 is provided with anysuitable formations, such as recesses typically indicated at 19,adapting it for engagement by a suitable wrench. As will be seen in thedrawings, the tubular part 151) is threaded from its extremity to adistance approximately coplanar with the face 17. An annular groove 20is sunk into the front of the hub, radially inside annular face 17, andto a depth below the plane of face 17, the inner side wall of saidgroove being defined by an inner extent of the tubular portion 15b, andthe outer side wall thereof extending inwardly into the hub from theinner boundary of the annular face 17. Lodged in this groove 20 is asynthetic rubber sealing ring 21, of the well known O-rin-g type, andthis sealing ring is squeezed between the bottom of groove 20 and thesurface of wall 13, as shown. Attention is directed to the fact that thebase port-ion'of the tubular member 15b and the inner side wall of thegroove 20 are shaped and dimensioned to clear the opposing face of wall13 around aperture 14, no shoulder or abutment engageable with the wallbeing permitted in this region which might otherwise, by engagementagainst wall 13, prevent or limit tight clamping of annular face 17against wall 13, or biting engagement of later described serrations onface 17 into Wall 13. With the nut 18 tightened only with fingerpressure, O-ring seal affords complete protection against moisturepassing through .the joint. It also seals against explosive pressure inevent of an explosion taking place to the left of panel 13.

The face 22 of nut 18 facing the inside surface of wall 13, and the face17 of collar 15, are formed with similar radially extending teeth orserrations, indicated at 22a and 17a, respectively, which teeth orserrations bite into the opposed :faces of wall 13 as the nut istightened on member 15b. 1 have found that these teeth may be placed onthe face 17 of collar 15, in which case they bite into the exterior faceof the wall 13 as the conduit is drawn inward owing to tightening of thenut; or they may be placed on the face 22 of the nut, in which case theydig or bite into the inside face of the wall 13 as the nut is tightened;or, as here shown, they may, if desired, be used in both locations. Theeffect, in either case, is to afford good, low resistance electricalcontact between the hub and the wall 13, as well as a mechanicalconnection of high torque value. That is to say, once tightened by meansof a wrench applied to the nut, extremely high torque must be applied tothe conduit to loosen the connection.

Thus, I have accomplished the objective initially set forth. The bitingengagement of the teeth into the surfaces of wall 13 assures a lowresistance coupling from the hub to the wall of the switch box.Mechanically, an extremely high torque value has been achieved. Thebiting engagement of the teeth 17a on the annular hub face 17 into thesurfaces of the switch box wall resist effort to turn the hub up to anexceedingly high torque much beyond the necessities of safety, and wellabove code requirements. Finally, a highly effective moisture seal isafforded, completely protecting against entrance of moisture even thoughthe box be exposed to the weather. Tests have shown that the hubprovided by the present invention meets existing specifications in therespects noted above with a high margin of safety.

In addition, the hub provided by the invention will be seen to be simpleand inexpensive in construction, and it will further be seen that it isinstalled with a minimum of effort and consumption of time. It is merelynecessary to thread the collar onto the conduit, insert the seal,introduce the portion 15b of the external hub part '15 through theprepared aperture in the wallet the switch box, and apply the nut. Theinstallation procedure will be seen to be of a most simple character.

In FIG. 5, I have shown a modifica-tionwherein the sealing ring isplaced inside the nut rather than accom modated within the collar. Thus,in this case (all other parts remaining as in the first describedembodiment, and identified by corresponding reference numerals), anannular groove 26 is formed in the face of the nut 18, and lodgedtherein is a sealing ring 27, again of the conventional O-ring type. Ifdesired, of course, sealing rings may be placed in both the collar 15and the nut 18. It is found on test, however, that a single such seal isentirely adequate.

The joint of the invention has been described in the foregoing primarilyin its application to electrical conduit connections to sheet metalwalls. It will be evident, however, that the joint may be used for otherpurposes. For example, it might be used to provide a liquid-tight jointof high mechanical security between a tank and an inlet or outlet pipe.Various other applications will suggest themselves to those skilled inthe art.

The drawings and description have shown present illustrative embodimentsof the invention, and have suggested a certain specific applicationthereof. It is to be understood, however, that these are forillustrative purposes only, and that various changes in design,structure, and arrangement may be made without departing from the spiritand scope of the appended claims.

I claim:

1. In a device of the character described, the combination of: a hubpart integrally formed with a collar portion and tubular portionsprojecting axially on opposite sides of said collar portion, one of saidtubular portions being threaded for coupling to a pipe and the otherbeing externally threaded and adapted to extend through an aperture in amounting wall, said collar portion having an outer periphery of largerdiameter than said externally v threaded tubular portion and having anannular wallengaging clamping face, adapted to engage one side of saidmounting wall, disposed in a plane normal to the axis of said hub andextending around, and facing axially in the same direction as, saidexternally threaded tubular portion, said annular clamping face havingteeth adapted to make biting engagement with the opposed face of saidmounting wall, said collar portion having an annular groove for anO-ring seal extending inwardly thereinto from the plane of said clampingface, said groove having inner and outer side Walls, said outer sidewall being defined by a surface spaced radially inwardly from the outerperiphery of said collar portion and forming the inner boundary of saidclamping face and said inner side wall being defined by a surface whichjoins said threaded tubular member at the base of the latter, saidlast-mentioned surface and said threaded tubular member being shaped anddimensioned to clear the opposing surface of said apertured wall wherebyto permit unrestricted engagement of said teeth on said annular clampingface with the surface of said mounting wall; and a clamping nut threadedon said externally threaded tubular portion having a clamping faceopposed to said clamping face on said collar portion and adapted toengage the other side of said mounting wall.

2. In a device of the character described, the combination of: a hubpant integrally formed with a collar portion and tubular portionsprojecting axially on opposite sides of said collar portion, one of saidtubular portions being threaded for coupling to a pipe and the otherbeing externally threaded and adapted to extend through an aperture in amounting wall, said collar portion having an outer periphery of largerdiameter than said externally threaded tubular portion and having anannular wall-engaging clamping face, adapted to engage one side of saidmounting wall, disposed in a plane normal to the axis of said hub andextending around, and facing axially in the same direction as, saidexternally threaded tubular portion, said collar portion having anannular groove for an O-ring seal extending inwardly thereinto from theplane of said clamping face, said groove having inner and outer sidewalls, said outer side wall being defined by a surface spaced radiallyinwardly from the outer periphery of said collar portion and forming theinner boundary of said clamping face and said inner side wall beingdefined by asurface which joins said threaded tubular member at the baseof the latter, said last-mentioned surface and said threaded tubularmember being shaped and dimensioned to clear the opposing surface ofsaid apertured wall whereby to permit unrestricted engagement of saidannular clamping face with the surface of said mounting wall; and 'aclamping nut threaded on said externally thread-ed tubular portionhaving a clamping face opposed to said clamping face on said collarportion and adapted to engage the other side of said mounting wall, atleast one of said clamping faces having teeth adapted to make bitingengagement with said mounting wall.

References Cited in thefile of this patent UNITED STATES PATENTS1,833,462 Hagist Nov. 24, 1931 2,055,130 Hotchkin Sept. 22, 19362,147,254 Hinderliter' Feb. 14, 1939 2,343,235 Bashark Feb. .29, 19442,452,184 Cole Oct. 26, 1948 2,462,023 Johanson Feb. 15, 1949 2,523,585Mueller Sept. 26, 1950 2,554,456 Coleman May 22, 1951 2,676,037 MuellerApr. 20, 1954 2,701,871 Ranch Feb. 8, 19555

1. IN A DEVICE OF THE CHARACTER DESCRIBED, THE COMBINATION OF: A HUB PART INTEGRALLY FORMED WITH A COLLAR PORTION AND TUBULAR PORTIONS PROJECTING AXIALLY ON OPPOSITE SIDES OF SAID COLLAR PORTION, ONE OF SAID TUBULAR PORTIONS BEING THREADED FOR COUPLING TO A PIPE AND THE OTHER BEING EXTERNALLY THREADED AND ADAPTED TO EXTEND THROUGH AN APERTURE IN A MOUNTING WALL, SAID COLLAR PORTION HAVING AN OUTER PERIPHERY OF LARGER DIAMETER THAN SAID EXTERNALLY THREADED TUBULAR PORTION AND HAVING AN ANNULAR WALLENGAGING CLAMPING FACE, ADAPTED TO ENGAGE ONE SIDE OF SAID MOUNTING WALL, DISPOSED IN A PLANE NORMAL TO THE AXIS OF SAID HUB AND EXTENDING AROUND, AND FACING AXIALLY IN THE SAME DIRECTION AS, SAID EXTERNALLY THREADED TUBULAR PORTION, SAID ANNULAR CLAMPING FACE HAVING TEETH ADAPTED TO MAKE BITING ENGAGEMENT WITH THE OPPOSED FACE OF SAID MOUNTING WALL, SAID COLLAR PORTION HAVING AN ANNULAR GROOVE FOR AN O-RING SEAL EXTENDING INWARDLY THEREINTO FROM THE PLANE OF SAID CLAMPING FACE, SAID GROOVE HAVING INNER AND OUTER SIDE WALLS, SAID OUTER SIDE WALL BEING DEFINED BY A SURFACE SPACED RADIALLY INWARDLY FROM THE OUTER PERIPHERY OF SAID COLLAR PORTION AND FORMING THE INNER BOUNDARY OF SAID CLAMPING FACE AND SAID INNER SIDE WALL BEING DEFINED BY A SURFACE WHICH JOINS SAID THREADED TUBULAR MEMBER AT THE BASE OF THE LATTER, SAID LAST-MENTIONED SURFACE AND SAID THREADED TUBULAR MEMBER BEING SHAPED AND DIMENSIONED TO CLEAR THE OPPOSING SURFACE OF SAID APERTURED WALL WHEREBY TO PERMIT UNRESTRICTED ENGAGEMENT OF SAID TEETH ON SAID ANNULAR CLAMPING FACE WITH THE SURFACE OF SAID MOUNTING WALL; AND A CLAMPING NUT THREADED ON SAID EXTERNALLY THREADED TUBULAR PORTION HAVING A CLAMPING FACE OPPOSED TO SAID CLAMPING FACE ON SAID COLLAR PORTION AND ADAPTED TO ENGAGE THE OTHER SIDE OF SAID MOUNTING WALL. 